Department of Microbiology, Federal University Dutsin-Ma, Katsina State, Nigeria.
Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA, USA.
J Glob Antimicrob Resist. 2020 Dec;23:340-344. doi: 10.1016/j.jgar.2020.10.005. Epub 2020 Nov 6.
Use of chloramphenicol or its veterinary analogue florfenicol can selectively favour antibiotic-resistant bacteria. Understanding how resistance is mobilised and disseminated among pathogens is vital in knowing how different bacterial taxa might serve as reservoirs of these genes for pathogenic bacteria.
Bacterial isolates (n=30) were selected on the basis of multidrug resistance and resistance to florfenicol from among 296 bacteria originally isolated from drinking water distribution systems in Southwestern Nigeria. Bacterial identification, minimum inhibitory concentration (MIC) determination for florfenicol, PCR detection of florfenicol resistance genes (floR, fexA and cfx) and sequence analysis were employed to characterise the isolates.
According to sequence data (16S rDNA, v2-v3 region), 30strains were selected, includingPseudomonas spp. (43.3%), Serratia spp. (13.3%), Proteus spp. (26.7%), Acinetobacter spp. (13.3%) and Providencia rettgeri (3.3%). MICs ranged between >16μg/mL and >1024μg/mL. floR was the only resistance gene detected (11/30; 36.7%). The majority of floR-positive isolates (8/11; 72.7%) were Proteus spp. All floR sequences shared 100% identity and 1-2 synonymous substitutions relative to other published sequences.
floR-positive strains in this study were originally selected randomly without antibiotics. Finding floR in four genera without selective enrichment is consistent with widespread distribution of this resistance trait in drinking water systems in Nigeria. Further work is needed to determine whether human and veterinary antibiotic use practices in Nigeria are contributing to proliferation of this important antibiotic resistance trait and to determine whether the presence of floR-producing strains is compromising human and animal health.
使用氯霉素或其兽医类似物氟苯尼考可能会选择性地有利于抗生素耐药菌。了解耐药性如何在病原体中转移和传播对于了解不同的细菌类群如何作为这些基因的储存库对于病原菌至关重要。
根据从尼日利亚西南部饮用水分配系统中最初分离的 296 种细菌中对多药耐药性和氟苯尼考耐药性的选择，从 30 种细菌分离物（n=30）中进行选择。采用细菌鉴定、氟苯尼考最小抑菌浓度（MIC）测定、氟苯尼考耐药基因（floR、fexA 和 cfx）的 PCR 检测和序列分析来对分离物进行特征描述。
根据序列数据（16S rDNA，v2-v3 区），选择了 30 株菌株，包括假单胞菌属（43.3%）、沙雷氏菌属（13.3%）、普罗维登斯菌属（26.7%）、不动杆菌属（13.3%）和雷特氏菌属（3.3%）。MIC 范围在>16μg/mL 和>1024μg/mL 之间。仅检测到 floR 一个耐药基因（11/30；36.7%）。大多数 floR 阳性分离株（8/11；72.7%）为普罗维登斯菌属。所有 floR 序列与其他已发表的序列共享 100%的同一性和 1-2 个同义突变。
本研究中 floR 阳性菌株是随机选择的，没有使用抗生素。在没有选择性富集的情况下，在四个属中发现 floR 与该耐药特征在尼日利亚饮用水系统中的广泛分布一致。需要进一步研究以确定尼日利亚的人类和兽医抗生素使用实践是否助长了这种重要的抗生素耐药性特征的扩散，并确定 floR 产生菌株的存在是否正在损害人类和动物健康。
